Treating hydrocarbon oil



Jan.. 4, i938. R. E. MANLEY TREATING HYDROCARBON OIL Fuga June 27', 195os Mmw A CRNEY Patented Jan. 4, 1938 K i i' UNITED STATES PATENT OFFICETREATING HYDROCARBON OIL Robert E. Manley, Port Arthur Tex., assignor toThe rllexas Company, New York, N. Y., a corporation of DelawareApplication June 27, 1930, Serial No. 464,331

6 Claims. (Cl. 196-18) This invention relates to improvements intreattransparency and luster at normal low atmosing parainc Waxcontaining hydrocarbon oil, pheric temperature. more particularlydistillate oils, in the lubricat- It is to be understood that oildewaxed by the ing oil range to remove the paraine Wax, the centrifugemethod is not necessarily the only presence of which in the final oil isundesirable; dewaxed oil which may contain a small amount 5 theinvention also relates to the removal of those of par-aine, but an oilwhich has been dewaxed Wax constituents remaining in the oil after debyother processes may also contain a small Waxing by any of the prior artmethods. amount of paraine.

Treating hydrocarbon oil to remove the par- Accordingly, the presentinvention is a very l0 afne constituents therefrom is known in theinuseful and valuable adjunct to any dewaxing 10 dustry as dewaxing theoil. Among the several process and it has for its chief object theremoval methods of dewaxing hydrocarbon oil which are of such paraihneas remains after the primary depracticed is that of mixing the oil to betreated Waxing Step iS finished. with a less viscous solvent oil, suchas naphtha, A clear understanding of the details of the inlf chillingthe mixture to crystallize or precipitate vention may be had byreferring to the following tluwxy cotnstitlients andtth centriflfigingle esicription id the accompanying dravvingfillusf-1 c e mix ure osepara e e Wax rom e ra mg 1n agramma 1c e eva 1on a pre erre mixture ofoil and solvent. embodiment of apparatus suitable for practicing Whilethis is a Widely practiced and economithe plOCeSS, and Whioh apparatus,for the H1051? cal mode of operation, it does have certain limitapart,iS Substantially Similar to that described in 2o tions outside of Whichthe operation of the procmy U. S. Patent No. 1,825,324. ess becomesuneconomical. For example, after the The Oil to loe deWaXed, foreXalrlDle, a WaX-bear- Wax containing oil is mixed with a solvent, oras` irlgkoyllinder Stock fraftiorl, s introduced from a it iscommonlycalled cut-back, the mixture or lian into a mixing ank whereinit iS 11h01'- cut-back stock is chmod to -10 or 20 F. at oushly mixedwith a solvent Such as petroleum 25 which temperatures the waxyconstituents wi11 nephtha, and delivered from a tank 3. The protend toprecipitate, and it is then delivered to a Dorllon of WaX-bearlng 011 toSOlVelll? may Vary, centrifuge machine Where the separation of the foreXamlole, from to about 70% by Volume Wax from the oil is accomplished.Even though 0f the Solvent. 'I'he dlluted oil 1s then forced by 3 Ehecuiibacis miei mi??? dsine etmueisi unhitlfttvitiii' 30 romtecler rougmsuae cannes o the centrifuge, it is impossible to prevent it from tionof Solid and Semi-Solid WaX Constituents c011- heatingt up soimewhat andcotneqilently it may talld tllllell. t t 't ted be cen rifuge atapproxima ey when it e o 1 e mlX ure Con alnlrlg preolpl a o5 has beenchilled to the previously mentioned tem- WaX iS then delivered to acentrifuge 5 l30 eieC 3.5 Parature which is Considered to ba Within theseparation between the wax constituents and the economical limits ofthis type of Operation o1l. The Wax constltuents are removed from theThe characteristics of the parafne to be reentnfue tg; tllfl forth Ofetrolatuml Wlichkis` moved from the oil may be such that all of itfralmtl t 011g atplpe Cba lecvllg an 40 does not precipitate or collectin removable or Ofrhlr Heuiealglobrlr femsl vch the 40 fiplleormf attutemseuloliey E? petrolatum has been separated are drawn oi na es egosep r nt t. y f th e from the centrifuge through a line 9 to a reor SomeOt er reason a ,a por Iorio ,e par" ceiving tank I0. During passagethrough the ane may b? thrown back milo Sollltlon Wlth the centrifuge,the temperature of the oil may have o1l. Accordingly, when treatlng oilby the cenbeen raised apprecably and recoolng may trlfuge method l??remflv? the paramne @Qnslltu' therefore, be necessary or desirable, orcooling to ents and Operatmg Within economical hunts a a still lowertemperature, for that matter, prior Small portion of the parcfne willremain m the to subjecting the oil to the subsequent filtration o il.`This is extremely objectionable because a step for the removal ofremaining wax. The oil 50 rlSe 1n the pour test of the 011 occurs upononli7 the mixture 1s, therefore, dehvered from the tank m slightestincrease of the paraiine content. It is by a, pump and conducted througha, chiller I2 also objectionable because an otherwise highly wherein itis subjected to such further cooling treated oil containing more than atrace of par as may be desired.

aine Will become cloudy, that is, it will lose its The cooled mixture isthen delivered to a mixer 55 I3 wherein iilter-aid material, such asdiatomaceous earth, is admixed with the oil. The filter-aid material isdelivered to the mixer from a tank I4, either in the form of a drypowder or in the form of a slurry, formed by mixing the filter-aidmaterial with naphtha or other solvent. The mixer I3 is provided withsuitable mixing or stirring means in order to eiect thorough mixing ofthe filter-aid material with the oil.

After the addition of the iilter-aid, the mixture may, if desired, besubjected to additional cooling by circulating the contents of the mixerI3, or a portion thereof, through a separate chilling coil I5.

The cold mixture of suspended wax and iilteraid material is drawn offfrom the mixer I3 by a pump I6 and delivered to a filter Iladvantageously of the pressure type.

The oil passes through the iilter and is discharged therefrom through apipe I8 intofa receiving -tank I9. The dewaxed oil collecting in thistank may then be drawn 01T for the purpose of recovering the solventtherefrom.

At the end of the filtering cycle, the contents of Y the iilter aredisplaced by means of gas introduced to the filter shell through acooling coil 20 and pipe'ZI. The gaseous displacing media may be aninert gas, such as flue gas. Following this displacing step, the iiltercake of wax and filter-aid material may be subjected to w-ashing withfresh solvent liquid delivered to the iilter by a pump 22 from a tank23. This washing solvent is passed through the iilter cake anddischarged from the filter through a pipe 24 into a receiving tank 25.This washed solution may be used for subsequent washings until theconcentration of the dissolved oil has reached the point where it isdesirable to subject the solution to evaporation to recover the solventand separate the oil.

After washing, the filter cake may be dried by forcing cold gastherethrough from the cooler 20 previously referred to. The filter cakeis discharged from the lter shell into a receiver 26 where it may betreated with warm solvent or by other means for the separation of waxfrom the diatomaceous earth, after which the earth may be returned tothe vessel I4 and used again for dewaxing further stock.

4In practicing the improved step, the dewaxed' oil is delivered from thecentrifuge S or other dewaxer while still cool, through the chiller I2,which further reduces the temperature of the oil only slightly, into amixer I3, where -a small amount of filter-aid material, say only threeor four pounds per barrel of oil is added and the oil and the filter-aidthoroughly mixed therein. The mixture is then withdrawn from the mixerI3 and passed through the filter Il from which the filtrate or paraffmefree oil is withdrawn, While the filter-aid material andthe paraiiineconstituents being removed collect in the interior of the filter and areultimately removed.V The magnitude of the entire equipment, that is, thechiller, the mixer and the filter, depends, of course, upon thedesirable rate of movement of the oil therethrough and as the improvedprocess is capable of being operated at high relative rates, thepartially dewaxed oil from a number of centrifuges or several filtersmay be run through a single unit of relatively small size in thepractice of this process. In some instances it may be of advantage toadd the filter-aid to the partially dewaxed oil and to then chill themixture rather than chill the oil and then add the filter-aid asdescribed above.

Another manner of practicing the improved process is to slightly furtherchill the partially dewaxed oil and then pass it through a filter, theleaves or filtering surfaces of which have been previously coated with asuitable filter-aid material to form a porous coat or cake thereonpervious to oil but impervious to waxy material.

Still another manner of practicing the improved process is to slightlyfurther chill the partially dewaxed oil and simultaneously chill apreviously prepared pumpable or otherwise movable fluent slurry offilter-aid material and naphtha or other solvent, mix the chilled oiland the chilled slurry and iilter this mixture. This procedure offers aparticular advantage in that by chilling the filter-aid material as wellas the wax containing'oil before mixing the temperature of the chilledoil is not raised as it would be if iilter-aid at atmospherictemperature was added.

The process of the present invention is capable of being practicedsuccessfully in a number of ways and it is not intended that its spiritand scope be limited by the descriptive terms employed, but rather bythe appended claims.

What I claim is:

l. The process of dewaxing hydrocarbon lubricating oil to yield an oilof low pour test and free from cloudiness due to precipitated wax attemperatures substantially above the temperature at which the oil willpour, which comprises chilling the oil to a temperature at whichprecipitation of the wax constituents occurs, separating the bulk of theprecipitated wax from the oil in the absence of a solid, inert materialsuch as diatomaceous earth, then subjecting the chilled partiallydewaxed oil to filtration in the presence of a filter-aid material such'as diatomaceous earth at a temperature substantially the same as thetemperature at which the oil was partially dewaxed whereby thecomparatively small quantity of wax remaining in the oil is removed.

2. The process of dewaxing hydrocarbon lubricating oil to yield an oilof low pour test and free from cloudiness due to precipitated wax attemperatures substantially above the temperature at which the oil willpour, which comprises chilling the oil to a temperature at whichprecipitation of the wax constituents occurs, separating the bulk of theprecipitated wax from the oil by difference in specific gravity and inthe absence of a solid, inert material such as diatomaceous earth, thensubjecting the chilled partially dewaxed oil to iiltration in thepresence of a filter-aid material such as diatomaceous earth at atemperature substantially the same as the temperature at which the oilwas partially dewaxed whereby the comparatively small quantity of waxremaining in the oil is removed.

3. The process of dewaxing hydrocarbon lubricating oil by a methodinvolving centrifuging, to yield an oil of low pour test and free fromcloudiness due to precipitated wax at temperatures substantially abovethe temperature at which the oil will pour, which comprises chilling theoil to a temperature at which precipitation of the wax constituentsoccurs, centrifuging the chilled oil whereby the bulk of the waxconstituents are separated from the oil, then subjecting the chilledpartially dewaxed oil to liltration in the presence of a lter-aidmaterial, whereby the comparatively small quantity of wax remaining inthe oil after centrifuging is removed.

4. The process of dewaxing hydrocarbon lubrieating oil by a methodinvolving centrifuging, to

yield an oil of low pour test and free from cloudiness due toprecipitated wax at temperatures at which the oil will pour, whichcomprises chilling the oil to a temperature at which precipitation ofthe wax constituents occurs, centrifuging the chilled oil whereby thebulk of the wax constituents are separated from the oil, then subjectingthe chilled partially dewaxed oil to filtration in the presence of alter-aid material at a temperature substantially the same as thetemperature at which the oil was centrifuged, whereby the comparativelysmall quantity of wax remaining in the oil after centrifuging isremoved.

5. The process of dewaxing hydrocarbon lubricating oil by a methodinvolving centrifuging, to yield an oil of low pour test and free fromcloudiness due to precipitated wax at temperatures substantially abovethe temperature at which the oil will pour, which comprises chilling theoil to a temperature at which precipitation of the wax constituentsoccurs, centrifuging the chilled oil whereby the bulk of the waxconstituents are separated from the oil, subjecting the chilledpartially-dewaxed oil to filtration in the presence of a filter-aidmaterial, whereby the comparatively small quantity of wax remaining inthe oil after centrifuging is removed.

6. In the dewaxing of mineral lubricating oil containing wax, includinga small amount of Wax responsible for cloudiness in the oil and which isnot removed with the bulk of the wax by centrifuging, wherein the oil ismixed with a solvent, chilled to precipitate wax, and the precipitatedwax removed therefrom, the method of removing the wax comprisingsubjecting the oil to both centrifuging to remove the bulk of the Waxconstituents and filtering in the presence of a lteraid material toremove cloud-forming wax, thereby yielding lubricating oil of low pourtest and free from cloudiness due to precipitated Wax at temperatures atwhich the oil will pour.

ROBERT E. MANLEY.

